His research interest includes environmental acoustics, noise control engineering and sound design, which are investigated through psycho-acoustical evaluation. Recently, he has been focused on the issues concerning the sound of next generation vehicles (such as electric or hybrid electric vehicles, EV/HEV) to discuss future road traffic noise and urban sound environment.

Pedro Poveda-Martinez, Mizuki Kawaguchi, Katsuya Yamauchi, Jaime Ramis-Soriano, Sound pleasantness of electrically adjustable exterior mirrors in vehicles, Applied Acoustics, doi.org/10.1016/j.apacoust.2018.09.009, 143, 1, 190-199, 2019.01, Consumers increasingly demand high quality products, forcing manufacturers to a greater effort when designing. During the last years, the noise has become a key factor in valuing a product, so the use of psychoacoustic techniques has been extended considerably. The automotive sector has always taken into consideration the noise when designing vehicles. A large number of tools and analysis methods have been developed in order to determine the sound quality of their products. Although the first efforts focussed on establishing the sound quality of the propulsion system, they rapidly spread to other parts of the vehicle like doors, powered windows, etc. The present work focuses on studying the behaviour of electrically adjustable exterior mirrors in vehicles. In order to analyse the noise produced by this kind of devices, four different samples were measured in a semi-anechoic chamber. To establish the pleasantness descriptor of the samples, sixty-two subjects were exposed to an auditory test using two different methods: paired comparison and ranking procedure. The experiments were carried out in three different laboratories: University of Kyushu in Japan (JP), University of Coimbra in Portugal (PT) and University of Alicante in Spain (SP); leading to a cross-cultural study. The results showed a great similarity between the preferences obtained by the two methods. .

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Katsuya Yamauchi, Daniel Menzel, Masayuki Takada, Koji Nagahata, Shin Ichro Iwamiya, Hugo Fastl, Psychoacoustic examination of feasible level of additional warning sound for quiet vehicles, Acoustical Science and Technology, 10.1250/ast.36.120, 36, 2, 120-125, 2015.03, The reduced noise of electric and hybrid electric vehicles has been of particular concern because of the potential danger that these vehicles pose to pedestrians when their approach is inaudible against background noise. To address this issue, the use of additional warning sounds in such vehicles is being considered in various countries. The aim of this study was to examine the feasible level of the warning sounds in some urban environments. The levels of three candidate warning sounds (sound of car horn, engine sound, and band-pass noise) were adjusted by the study subjects against four types of urban background noise presented in a laboratory environment. The subjects were asked to adjust the level of the warning sounds so that they were reliably audible or just detectable. The results showed that the level of background noise and type of warning sound significantly affected the perception of the warning sounds, but there was no significant cross-cultural difference between the German and Japanese subject groups. The observations showed that a warning sound that was reliably audible in a particular environment might be inaudible in another environment approximately 10 to 20 dB noisier. The results were also compared with current recommended levels of warning sounds for quiet vehicles..

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Katsuya Yamauchi, Takayuki Shiizu, Fumio Tamura, Yuichiro Takeda, Relationship between frequency shifting of vehicle sounds and acceleration impression, Acoustical Science and Technology, 10.1250/ast.36.135, 36, 2, 135-137, 2015.03, A paired comparison test using audio and visual stimuli was conducted to examine the relationship between frequency shifting and the acceleration impression of vehicles. The results showed that frequency shifting can enhance the vehicles' acceleration impression for both pedestrians and passengers in the vehicles. It was also shown that the acceleration impression is affected by not only the rate of shifting but also its band. The majority of the stimulus conditions that contained a 2,000-Hz-band component had a positive effect on the acceleration impression. The band and rate of frequency shifting also had an effect on the harmonization between the impression of audio and the visual acceleration. In the future, our aim is to investigate a comprehensive impression and to explore the capabilities of a designed application. Moreover, the actions of a driver may potentially have an effect on the acceleration impression, and hence, an examination using a driving simulator is also a part of our future work..

Katsuya Yamauchi, Questionnaire Survey on the Encounter Experience with Quiet Vehicles, Inter-noise 2017, 2017.08, Relative quietness of electric or hybrid electric vehicles is one of the most important topics in environmental acoustics. Although reduced vehicle noise is eligible for urban sound environment, it is also a matter of pedestrians’ safety concern. Hence, regulations regarding additional warning sounds for the quiet vehicles have been developing in Japan as well as in global. Recently the UN-regulation regarding the warning system to compensate their quietness by additional warning device, Acoustic Vehicle Alerting System (AVAS) according to the regulation, has been approved. Those kinds of measures should be carefully discussed. Several studies have been conducted in different institutions to examine the feasible sound design for the warning to be detected in urban noise environment. This paper introduces the result of a questionnaire survey on the risks and encountering experiences with quiet vehicles on streets, and also on the knowledge and opinion to the additional warning sounds. The survey was conducted via internet form, and collected answers from Japanese younger generation. The result was compared with the similar survey previously conducted by the author..

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Katsuya Yamauchi, Saki Liu, Keita Suzuki, Takuya Nomura, Developing Method Describing Impression of Unknown Sounds through Non-Acoustic Event —for a Sound Design of Electric Vehicle—, Inter-noise 2016, 2016.08, It is important, however, to know the factors that make sounds to recall EVs particularly to design the warning sounds for EVs to ensure awareness of them. However, most of people have not had experience to see, listen to, or drive electric vehicles (EVs), then the sound of EVs are unknown for most of people. To understand these factors, we developed a method to know an impression of unknown sounds through non-acoustic events related to the impression of running EVs, in this study those were the impression of road environments or the driving impression. We assumed that if the impression of the non-acoustic events were highly related to running EVs, the sounds that had similar impression could be evaluated to harmonize with EVs. At the first stage of the presenting method, we conducted a large scale social survey to collect enough number of words that correspond with the non-acoustic events. The collected answers were divided some clusters which represent the non-acoustic events by by hierarchical cluster analysis using the mutual occurrence frequency between two words. Then the impression of the landscapes that were evoked by each word cluster was examined through the SD-method subjective evaluation experiment. As the result, we described the impression of the sounds that would potentially harmonize with driving EVs..

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Katsuya Yamauchi, Soichi Sasaki, Shinya Yamashita, Masaru Takeshita, SUBJECTIVE EVALUATION OF VEHICLE DOOR MIRROR NOISES WITH DIFFERING CLEARANCES BETWEEN PARTS, The 22nd International Congress on Sound and Vibration (ICSV), 2015.07, As a part of a study on the effects of mounting conditions of vehicle door mirror on aerody- namic noise, hearing impression of the noises were examined by a series of subjective evalu- ations. We focused on the difference of aerodynamic noise caused by the differing clearance between the mounting base and door panel, and that between the base and mirror visor. To examine the effects of these clearances on hearing impression, a series of subjective evalua- tion experiments were conducted. The aerodynamic noises were recorded in a wind tunnel using several mirror models that had different clearances. The acoustic transfer function be- tween door mirror and ear position of a driver, which was previously measured, was convo- luted to the recorded noises. To evaluate the relative difference on hearing impression, we conducted a similarity evaluation using paired-comparison method (Experiment 1). As the result of the first experiment, we obtained two-dimensional hearing impression space, then we confirmed the significant difference between the mounting clearances. The relative posi- tions of stimuli on the impression space indicated that the impression was affected not only by A-weighted sound pressure level but also the other aspects. To confirm the qualitative meaning of the relative difference, the other experiment using semantic differential (SD) method was conducted (Experiment 2). The relationship between the hearing impression space and the rating values of SD-scales was discussed by the multi-regression analysis. The results suggested that a larger clearance between the mounting base and mirror visor resulted a noisy and bright impression..